kick in the teeth
If you describe the way someone treats you as a kick in the teeth, you mean that they treat you badly and unfairly, especially at a time when you need their support
She was dismissed from her job, which was a real kick in the teeth after all the work she'd done.
to disappoint someone by telling them the unpleasant truth about something or someone that they had a good opinion of, or respected
I hate to/I'm sorry to disillusion you, but pregnancy is not always wonderful - I was sick every day for six months.